[pypy-issue] [issue1738] struct.unpack incompatibility with cpython

Armin Rigo tracker at bugs.pypy.org
Wed Apr 23 08:52:33 CEST 2014

Armin Rigo <armin.rigo at gmail.com> added the comment:

My point is that on CPython, programs that do str() on the result and are
unhappy with the trailing L are broken --- because they will get a trailing L on
some inputs.  Ryu's regression tests are possibly an exception, in that they are
not broken by relying explicitly on the absence of a trailing L, for a specific
input value chosen for the test.

We have to decide if it's worth taxing the jitted performance of all programs
that use unpack() by returning mixed types, in order to support this very
special compatibility requirement; or if we say that Ryu should just fix its
test to not rely on this detail (similar to how you need to add "gc.collect()"
in some tests that verify that __del__() was called).

If you have another example where the problem is not in a test, I'd be
interested. :-)

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